The present invention concerns a semiconductor device and a method of manufacturing the semiconductor device which can be utilized suitably to semiconductor devices, for example, using nitride semiconductors.
In recent years, semiconductor devices using group III-V compounds having a larger bang gap than Si have been noted. Among them, development has been progressed for semiconductor devices which are power MISFET (Metal Insulator Semiconductor Field Effect Transistor) using gallium nitride and which enable normally off operation in view of high voltage withstanding and high speed switching characteristics.
For example, Japanese Unexamined Patent Application Publication No. 2008-306083 discloses a group III-V nitride semiconductor field effect transistor having a gradient portion at the bottom of a gate electrode.
Further, Japanese Unexamined Patent Application Publication No. 2012-248636 discloses a field effect transistor having a channel layer and 2 DEG at a hetero-junction interface between the channel layer and an electron supply layer.